Gas turbine and like engine



Feb. 10, 1953 A. A. LOMBARD 2,628,067

GAS TURBINE AND LIKE ENGINE Filed June 16, 1947 2 Sl-IEETS-Sl-IEET lFeb. 10, 1953 A. A. LOMBARD GAS TURBINE AND LI KE ENGINE 2 SHEETS-SHEET2 Filed June 1 1947 Ina 8% 4 in an cI ZaWzZaY'zZ 7 1%; v

Patented Feb. 10, 1953 Adrianibert Lombard, Clitheroe, England; as

signor to Rolls-Royce Limitedgjlrirby, England;

a British-company- Application Jun -16, 1947', Serial No; 754,355

" In Greatl Britain (funer l-8, 19 46 2-Claiins. (01.253 65) Thisinvention relates e e n n i h" h gh em er t s are eveloped, and has forits object to provide a construction and arrangement whereby the mainstructural elements of theengi'ne are adequately isolated from high'temperatures? According tothis'invention thereis provided in an axialflow turbine; an outerloadrcarrying or strength-ring securedto the"main: enginestructure and surrounding the turbine stationaryshroud-ring for the rotor blades to'provide a space therebetween servingto insulate the loadcarrying ring from the hot-gases.

A cording to another feature of the invention the exhaust structureiscarried on the said loadcarrying ring whereby loads on the exhauststructure are transmitted through the said ring to the main,engine-structure. The said ring further may provide a point of supportfor the-engine in its supporting structure.

According to another feature of the invention the inner stationaryshroud-ring is retainedin theload-carrying ring by loose spigots,andjina preferred construction the said, shroud-ring isconstructedinseparate segments.

According to another feature of, the invention the outerjload-carryingring aforesaid-may. be sandwiched between two rings provided each with aflange at its inner end whereon the inner segmental ring is spigoted.The use of these two separate rings further reduces the heatconductivity to the strength-element.

The space provided by this invention inside the load-carrying ring maybe an enclosure for stagnant gas, or means may be provided for supplyinga flow of cooling air to it.

According to another feature of the invention the outlet passage fromthe turbine-wheel, where the temperature of the gases is still high, isconstituted by an inner skin to provide an air-space between it and theouter skin which is secured through the load-carrying ring to the mainstructure oi the turbine, thereby providing an insulating air-spacebetween the hot gases and the outer casing; the said inner skin isconveniently in the form of a truncated cone welded at its end remotefrom the turbine-Wheel to the exhaustpassage for the hot gases.

Other features of the invention will be described with reference to aparticular embodiment of it illustrated in the accompanying drawings inwhich Figure 1 is a general view of the gas-turbineengine, and

Figure 2 is a fragmentary sectional view in a plane through the turbineaxis.

0 as -turb ne asdi e I Referring to Figure .1, the gasaturbi'nerenginecomprises an. air-"intake; Ill openingto. a. centrif-ugal compressor Hwhich deliverscompressed air. to a. seriesof combustion-chambers l2arranged -in a. ring around a. shaft.,drivingly connecting thecompressor'to a. single stage turbine situated; at [3 to whichthecombus'tion. products pass through anoszle-boxassembly I 4 and fromwhich i the exhaust gases; pass to an. exhaustassembly l5.

The Ymain'structure. of; thegas turbineeengine is constituted by thecompressor-casing, an intermediate casing; l6 within-thawing] of--combuStiOnchambers; andoan aperturedtring. l'i extendingbetweenthecasing; l6 at its inner radius, and theturbin'e stator orlnofzzleguide. vane structure at its outer radius; therapelfturesinthering, i 1serving for the vpassagejof :hot gases kfromthe combustion chambers?through necks. [91- to theturbine. The necks islalso. enclose thenozzle-. boxes I8 which supportat their; forward endsseating-ringsl-Zllwhich receive'th e delivery ends of 'theicc'rnb'ustion chambers 2..

The turbinecompr-ises a-turbine-wheel zl (see-v Figure 2)"carryingbladesd la-and amaint turbine stator-structure which,includesaring-Iikemema ber.-2.2 situated'i'n theplane of rtheturbineewheel 2|. The member 22 constitutes the load-carrying ringaforesaid which provides a point of support S as shown in Figure 1 forthe engine on the aircraft, other points of support being indicated at Talso in Figure 1. To ensure that the member 22 is not subject to thehigh temperatures existing within the turbine it is provided on eachedge with an inwardly-directed flange 23, to which flanges are boltedrings 24, 25, and an inner stationary shroud-ring 26 is provided lyingclosely around the outer ends of the turbine-blades 2Ia being looselyspigoted in or on the rings 24, 25. The shroud-ring 28 is thus locatedwithin and spaced radially from the member 22 to form a space 39thermally insulating the ring 22 from the efiects of the hightemperatures within the turbine.

The shroud-ring 2G is, in this construction, pro= vided withoutwardly-directed peripheral flanges 21 one of which constitutes themale member of a spigot and socket joint the female member of which isformed as an annular groove 28 in a flange 29 on the ring 24, and theother of which forms a spigot and socket joint with a flange 30 on thering 25. The shroud-ring 26 is formed as a series of segments and thespigot connections between the ring 26 and the rings 24, 25 arepreterably a loose fit so as to relieve the shroud-ring from any loadstresses, such stresses being transmitted through the ring 22 to themain enginestructure.

The space 39 between the member 22 and the segmental ring 26 may be anenclosure for stagnant gas or means may be provided for supplying 5 aflow of cooling air to it.

The flange 29 on the ring 24 provides in this construction the outercarrier-ring for the nozzle-guide-vanes 3! which are splined thereto.The thermal conduction between guide-vanes 31 and ring 24 is low due tothe splined engagement therebetween. The mounting of the nozzleguide-vanes form no part of this invention but they may conveniently bemounted as described in the specification of United States patentapplication No. 727,520, now Patent No. 2,605,997. It will be seenmoreover that the nozzle-boxes I8 are supported in the supporting ringI! so that the combustion products do not impinge directly on the ring11. A similar arrangement of nozzleboxes is more fully described in thespecification of United States patent application No. 733,912.

It will be seen therefore that the nozzle-box assembly, thenozzle-guide-vane assembly and the turbine are so constructed as toisolate the hot gases from the main support-structure of the enginebefore they reach th turbine; the gases however are still at ahigh-temperature after leaving the turbine-wheel and it is desirabl toprovide heat-insulation for the exhaust duct adjacent its connections tothe turbine-casing.

For this purpose there is provided at the inlet end of the exhaust duct32 which is secured to the member 22 by a support-ring 33 welded on theduct, an inner skin 34 spaced away from the duct 32 adjacent theturbine-wheel 2! to provide an insulating air-space 35.

The inner skin 34 in this construction is in the form of a truncatedcone whereof the larger diameter is adjacent the turbine-wheel toreceive the gases therefrom and the other end i welded to the innersurface of the exhaust duct 32 at a point 36 spaced away from theturbine-wheel and the strength member 22 which is to be protected fromexcessive heat. The shroud-ring 26 has a rearward extension 31 directedtowards the beaded edge 38 of the inner skin 34 to conduct the exhaustgases from the turbine into the in-- terior of the inner skin 34.

I claim:

1. In an axial flow turbine, a turbine rotor, axial-flow rotor blades onsaid rotor and a turbine stator structure comprising a turbine inletstructure, a mounting ring on said turbine inlet structure, a turbineexhaust structure, a mounting ring on said turbine exhaust structure, aloadcarrying ring sandwiched between and secured to said mounting ringsand surrounding said rotor blades, said two mounting rings extendingradially inwardly from said load-carrying ring and each having anaxially-extending flange at its inner diameter, said flanges extendingtowards each other to define two annular axially-extending recesses, anda substantially continuous stationary shroud ring for said rotor bladeslocated between said load-carrying ring and said rotor blades and spacedfrom said load-carrying ring to provide a space therebetween in theplane of the rotor blades and radially outwardly of the rotor blades,said shroud ring comprising a plurality of segments each having a pairof oppositely-extending axially-directed flange thereon, said segmentsbeing loosely supported at both ends in circumferential assembly by saidaxiallydirected flanges engaged in said recesses.

2. A construction according to claim 1 further comprising turbinenozzle-guide-vanes in said turbine-inlet structure and wherein saidmounting ring on said turbine-inlet structure provides a carrier forsaid turbine-nozzle guide-vanes.

- ADRIAN ALBERT LOMBARD.

REFERENCES CITED The following references are of record in the file ofthis patent; 4

UNITED STATES PATENTS Boestad et al June 7, 1949

